Pengaruh Variasi H2SO4 Pada Pembentukan Nanosilika Berbasis Batu Apung

Nanosilica was extracted by using NaOH, H2SO4 and HCl. The amounth of NaOH and HCl are 3,0 M and 1,0 M respectively. The titration using H2SO4 was varied of 4,0 M; 4,5 M; 5,0 M; 5,5 M; 6,0 M. The pumice powder was calcined for 4 hours at 500 ºC and the nanosilica powder was calcined for 5,5 hours at 800 ºC. The results of X-Ray Flouresence (XRF) showed nanosilica with the highest purity in variation of H2SO4 5,0 M at 95,32%. The results of the X-Ray Diffractometer (XRD) showed that pumice consistent the anorthite and albite phase. The variation of H2SO4 5,0 M produced an amorphous phase. The results of Transmission Electron Microscopy (TEM) show nanosilica particle size with variations of H2SO4 5,0 M in the range 4,8-11,3 nm with an average (7,62 ± 2,15) nm.

Evaluating the Effects of Nanosilica on Mechanical and Tribological Properties of Polyvinyl Alcohol/Polyacrylamide Polymer Composites for Artificial Cartilage from an Atomic Level

Due to the superior performances of nanosilica particles, this research has been designed to study their effects on the mechanical and trigological properties of a PVA/PAM polymer composite by a molecular dynamics simulation method. To realize the research objectives mentioned above, the molecular models of amorphous cells and sandwiched friction models for pure polyvinyl alcohol (PVA)/polyacrylamide (PAM) (component weight ratio is 1:1) and PVA/PAM/nanosilica (component weight ratio is 5.75:5.75:1) polymer composites were constructed and simulated, respectively. The simulation results of the mechanical properties show increases about 31.6% in the bulk modulus, 53.1% in the shear modulus, and 50.1% in the Young’s modulus by incorporating a nanosilica particle into a pure PVA/PAM polymer composite. Meanwhile, the changes in Cauchy pressure, B/G ratio, and Poisson’s ratio values indicate that incorporating a nanosilica particle into pure PVA/PAM weakened the ductility of the composite. Incorporating a nanosilica particle into a pure PVA/PAM composite also showed a decrease about 28.2% in the abrasion rates and relative concentration distributions of polymer molecules in the final friction models. Additionally, the binding energy and the pair correlation functions between a nanosilica particle and the polymer chains in a cubic cell demonstrate that incorporating nanosilica into PVA/PAM polymer composites improves the internal binding strength between different components through the forming hydrogen bonds. As a result, the mechanical and tribological properties of PVA/PAM polymer composites can be enhanced by incorporating nanosilica particles.

Effect of Nanosilica Particle Size on the Water Permeability, Abrasion Resistance, Drying Shrinkage, and Repair Work Properties of Cement Mortar Containing Nano-SiO2

This work presents the effect of nanosilica particle sizes on durability properties and repair work properties of cement mortar containing nanosilica (NS). Three different NS particle sizes of 12, 20, and 40 nm were used and compared with those of cement mortar without NS and cement mortar with silica fume (SF). Interesting results were obtained in which the particle size of NS affected directly the abrasion resistance and water permeability. NS with particle size of 40 nm is the optimum size and gave the highest abrasion resistance and water permeability. For repair work properties, cement mortars containing NS (12 and 20 nm) and SF experienced higher drying shrinkage than that of cement mortar without NS and then presented cracking behavior and debonding between the cement mortars and concrete substrate. Cement mortar containing 40 nm of NS gave the lowest drying shrinkage, the lowest crack number, and the highest adhesive strength. These results indicate that the particle size of NS affected not only the durability properties but also the repair work properties of cement mortar.

Effect of Nanosilica on Mechanical and Thermal Properties of Cement Composites for Thermal Energy Storage Materials

This research article presents the mechanical and thermal properties of cement-based composite for thermal energy storage materials. The effects of nanosilica particle size and concentration determined by mixing nanosilica particle size of 50 nm, using nanosilica were of 1-5 wt%. Thermal properties coefficients were tested using a direct measuring instrument with surface probe (ISOMET2114). The influence of nanosilica on the performance, such as compressive strength, bulk density, thermal conductivity, volume heat capacity and thermal diffusivity of hardened composite cement pastes were studied for future solar thermal energy materials with better performance. According to the development of thermal storage materials and their application environment requirement in solar thermal power, the specimens were subjected to heat at 350, and 900°C. It were observed that, before heating, the compressive strength is optimized at nanosilica amount of 4wt% at the age of 28 days. Moreover, after heating at 350 oC and 900°C, the thermal conductivity and volume heat capacity of the cement paste enriched with nanosilica were significantly lesser than that of the before heating one.

The Study of Physical and Thermal Conductivity Properties of Cement Paste Containing Nanosilica

This research was presented the physical and thermal conductivity properties of cement pastes containing nanosilica by mixing three nanosilica particle sizes of 12, 50 and 150 nm, using nanosilica of 1-5 wt%. The water-cementitious ratio (W/C) was 0.5 for all samples. Thermal property coefficients were tested using a direct measuring instrument with surface probe (ISOMET2114). The influence of nanosilica on the physical properties were compressive strength, bulk density, XRD and SEM respectively. The results indicated that the use of nanosilica as an admixture can reduce the thermal conductivity and lowered the bulk density of specimen. The cement paste with nanosilica particle size of 50 nm with 4 wt% nanosilica at the age of 28 days showed the optimized properties. The thermal conductivity was lowest at 0.913 W/m-K, the compressive strength was highest at 51.62 MPa and the bulk density was 1,806 kg/m3respectively. The compressive strength increases more than 50% higher than that of pure paste. The cement pastes with nanosilica particle sizes of 50 and 150 nm, have lower unit weight and thermal conductivity than typical control cement paste about 9% and 15% respectively. The nanosilica mixed cement paste is very interesting for energy saving when used as wall insulating material.

Experimental and Modeling Studies on Thermal Conductivity of Cement Composites Containing Nanosilica

This research article was presented the thermal conductivity of cement pastes containing nanosilica. The effects of nanosilica particle size and concentration determined by mixing three nanosilica particle sizes of 12, 50 and 150 nm, using nanosilica were of 1-5 wt%. The water to binder ratio of 0.5 was used. The thermal properties test were subsequently measured in terms of thermal conductivity coefficient using ISOMET 2114. The thermal conductivities of cement paste is thus numerically calculated and the predictions are compared with the existing experimental data. A unifying equation for four fundamental effective thermal conductivity structural models (Series, Parallel, one-dimensional heat flow, Maxwell’s model) was derived. The best prediction was provided by a composite model that combined the Maxwell’s model. Consequently, applications of nanosilica cement paste in building constructions may be an interesting solution in order to improve sustainability and building energy efficiency.